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CH activation and catalysis with iridium hydroxo and methoxo complexes and related chemistry

CH ACTIVATION AND CATALYSIS WITH
IRIDIUM HYDROXO AND METHOXO COMPLEXES
AND RELATED CHEMISTRY
by
William Joseph Tenn, III
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(CHEMISTRY)
August 2007
Copyright 2007 William Joseph Tenn, III

This dissertation describes a veritable smorgasbord of organometallic chemistry, including the use of transition metal methoxo and hydroxo complexes based on iridium(III) as homogeneous catalysts for the activation of hydrocarbon C-H bonds, the functionalization of a low valent rhenium methyl complex, and the design, synthesis, and study of related systems for the catalytic functionalization of hydrocarbons.; Chapter 1 introduces the CH activation reaction and catalytic functionalization of hydrocarbons via electrophilic systems, and discusses the problem of inhibition of electophilic catalysts by products such as methanol and water. Approaches towards the development of the next generation of catalysts that are active for CH activation in water are discussed.; Chapter Two describes a thermally and air stable iridium(III) methoxo complex that undergoes intermolecular CH activation of benzene with co-generation of methanol and the iridium-phenyl complex.; Chapter Three highlights a well-defined, iridium hydroxo complex that is competent for CH activation and long-lived, H/D exchange between benzene and water. An inverse dependence of the H/D exchange rate on added pyridine, deuterium kinetic isotope effects, and density functional theory calculations are consistent with CH activation proceeding via rate-determining benzene coordination followed by fast CH cleavage.; Chapter Four discusses the mechanism responsible for CH cleavage in (acac-O,O)2Ir(OCH3)(C6H6), which has been identified and described as an internal electrophilic substitution (IES) mechanism, on the basis of orbital changes and predicted reactivity. In the IES mechanism, the lone pair on a M-X ligand forms a X-H bond, while the orbital making up the M-X bond becomes a coordinating lone pair.; Chapter Five describes the synthesis and structural characterization, of novel, Rh(III), bis-acetylacetonate complexes. The first rational synthesis and characterization of the O-donor, air and water stable organometallic complex, (acac)2Rh(Ph)(CH3OH), and related analogs are reported.; Chapter Six discusses the synthesis, characterization, and CH activation reactions of a series of new organometallic, bis(hexafluoroacetylacetonato) rhodium(III) complexes. These complexes were found to be active for CH activation.; Chapter Seven summarizes the development of compatible functionalization reactions with a methyl rhenium species, for integration with the CH activation reaction of hydrocarbons by transition metal alkoxo complexes.

CH ACTIVATION AND CATALYSIS WITH
IRIDIUM HYDROXO AND METHOXO COMPLEXES
AND RELATED CHEMISTRY
by
William Joseph Tenn, III
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(CHEMISTRY)
August 2007
Copyright 2007 William Joseph Tenn, III